The invention relates to surgical devices having motor driven handpieces which receive rotatable surgical tools.
Surgical devices, e.g., for arthroscopic surgery, typically include a handpiece containing a motor and having a distal portion adapted to receive a surgical tool, e.g., an arthroplasty resector. In such systems, the distal tip of the surgical tool usually defines a vacuum passage through which fluid and tissue are removed from a patient's body during surgery. The passage extends from the distal tip of the surgical tool through the tool and into a drain tube in the handpiece which is connected to a suction device. Sometimes, however, the fluid and tissue also enter the motor through the space created between the motor housing and the rotating drive shaft, causing the motor to malfunction and corrode.
One known solution to this problem is to provide flexible lip seals or O-rings around the drive shaft which contact the surface of the drive shaft and seal it parallel to its axis of rotation. The O-rings and the lips of the lip seals, i.e., those portions of the seals which contact the drive shaft, are very flexible, e.g., formed of silicone rubber, or formed of a cover material and some type of filler such as Teflon.RTM. and a graphite compound. In addition, systems which use the O-ring and lip sealing techniques are also known to use close tolerance fitting of the bearings with the drive shaft to prevent the surgical device from rotating off center and pulling away from a portion of the seal, thereby allowing fluids to enter the motor housing.